[Nwallins]

The "trouble" is only when you want a single process to monopolize the entirety of CPU resources. In today's (and even yesterday's?) processing environment, there are often tens if not hundreds of processes running at once, and 5 or 15 of them may be "performance critical".

Are multicore architectures not able to distribute this sort of load?

[wmf]

On PCs it's common to have hundreds of processes sleeping, but rare to have more than one or two threads runnable.